Woodruff key found in the bottom of a 340 with 7qt. pan

Ok here goes, I've installed a few big block Chevy cams in the past and never seen a key like this before. I found one in the bottom of the 7 quart pan and no metal filings with it. Can't see how one could come out. The 340 was running when bought. Maybe the builder dropped one by mistake? Supposed to only have about 700 mi. on engine, but it's been bagged and sitting a few years. I'm going back to the standard pan and, SUPRISE, found it during the swap. Problem? Been told the only dumb question is the one not asked when you don't know. Thanks